Hi,
I was doing support lug calculation and the result of WRC107 stress calculation for sustainable loads showed that some of curve value exceeded. Finally, WRC107 stress summations show that the result was passed. Is it means that the size of support lug is applicable? I would appreciate if someone could help to explain this situation? Is it really matter that curve value exceeded?

Thank you.
WK Ng

WK Ng,

You need to read WRC107 and assess for yourself the effect of any values that exceed curve limits. The software will complete the WRC107 calculation and report any warnings that need to be checked.

The WRC107 curves are derived from the original work of Bijlaard and further modified by experimental data. As a result, WRC107 does not offer a 'one size fits all' solution. Whilst it is not uncommon for the curve values to be exceeded, there are some attachment/vessel geometries for which WRC107 is not applicable. For example WRC107 warns that "a portion of the original curves has been deleted in order to emphasize that the curves should not be used beyond the limits indicated" (also read Appendix A).

I would recommend that you check the specific curves where values have been exceeded and evaluate considering the curve actual value/limit value ratio as compared with the calculated/allowable stress ratio. The you may be able to discover whether "it really matter that curve value exceeded".

Alternatively, you could consider running the calculation again using PD 5500 Annex G.